The present invention relates to a sailing vessel comprising a hull, two outriggers, one on either side of the hull, a rudder, and rigging supporting at least one sail.
Moderns sailing vessels balance the wind-power forces acting on the sail via displacement of crew, water tanks, keel, etcetera. In this kind of boats, the force of the wind acting on the sail consequently is balanced by displacement of the centre of gravity. The moments of force must be balanced, i.e. the wind power multiplied by the distance from the keel or the centre-board centre to the sail centre is to be balanced relative to the keel displacement and/or the centre of gravity of the crew multiplied by the horizontal distance of the centre of gravity from the centre of the boat. In the case of non-planing boats, the speed through the water is limited to about half the speed of the wind. In addition, modern displacement-boat constructions are designed for an upper wind-force limit, known as the design wind. Wind speeds above the design wind do not increase the speed of the boat; instead, the surplus power is xe2x80x9cdumpedxe2x80x9d or caused to pass by.
It is previously known to arrange water-submerged hydrofoils to cause the boat to plane. However, the purpose of such hydrofoils is not to counter-act the wind-power moment, with the exception of the special case of sailing before the wind.
U.S. Pat. No. 3,747,549 describes a sailing vessel comprising on the windward side an outrigger with a wing thereon submerged into the water. By adjusting the angle of the wing, it becomes possible to adjust the counter-acting force on the sail.
U.S. Pat. No. 3,870,004 concerns another type of sailing vessel, which is more like a multi-hull boat. In addition, in this case a counter-acting force on the sail is achieved by means of a water-submerged wing. However, the counter-acting force is not generated by the water flow around the wing but rather by a frictional force. The principle of generation of the counter-acting force thus is essentially different.
In the case of these two prior-art vessels, a counter-acting force against the wind thus is obtained by means of one outrigger only, equipped with a water wing. In addition, it is not possible to fit these boat constructions with several outriggers, since the structure designed to sense the position of the wing and the mechanics of controlling it are adapted for one single wing. In addition, the construction as shown causes considerable friction and resistance to flow. The result is a considerable moment, and considerable rudder deflection is necessary to steer the boat back on course with consequential reduction of speed. In addition, the boat tends to luff strongly and has a tendency to haul the wind. Therefore, it can only sail before the wind and in addition on one bow only.
Consequently, it is one object of the invention to provide a vessel that is faster and makes more efficient use of the wind than do hitherto known boat constructions.
In accordance with the invention, a sailing vessel is provided, comprising a hull, two outriggers, one on either side of the hull, a rudder, and rigging supporting at least one sail. In addition, the vessel comprises wings secured to the outriggers and arranged to be located below the surface of the water during sailing, the leeward wing arranged, as the vessel moves through water, to exert an upwards directed force and the windward wing arranged to exert a downwards directed force to counter-act the rotational force from the sails.
The two wings offer almost equal resistance to the flowing water. As a result, the rotational moments that cause the course of the vessel to change, cancel each other out. In addition, this arrangement provides the further advantage that the load exerted on the vessel by the downwardly directed wing is largely compensated by the upwards directed force leeward. A centreboard or keel is no longer necessary to provide the sailing vessel with the force counter-acting the sail force that would turn the vessel leeward via the mast. Furthermore, less friction is generated when the leeward wing is given lift than if the entire lift were to be taken by the hull. Also, the hull offers larger resistance to flow, friction and loss through splashing, and so on, than does a water-submerged wing, which re-creates the energy consumed to displace the water ahead, in that the energy is recreated when the water molecules are xe2x80x9cre-positionedxe2x80x9d once the wing has passed. Because it becomes possible to eliminate keel or centreboard, the flow across a rudder positioned at the rear centre also becomes less turbulent, which reduces the resistance to flow to a fraction compared with conventional vessels.
Without a deflection of the leeward wing counter-acting the windward wing, a very strong force would, in the absence of a centreboard, have acted on the vertical profile components, in which the water wings preferably are secured. The latter would have been affected like swords or centreboards by very strong lateral forces. Because the leeward wing absorbs a large proportion of these forces, the vertical profile components can, however be relieved almost entirely. The vertical profile components do, however also prevent leeward drift. In order to prevent turning moments, the vertical profile components preferably are located oppositely the sail centre amidships, just as is done with a centreboard.
By means of the invention, it is estimated that speeds double the speed of the wind, may be obtained. In addition, the present sea yacht has no upper limiting wind speed, but as the wind speed increases and the velocity increases, also the counter-acting force of the water-submerged wing increases, and therefore the wind force may be balanced also under conditions of very strong winds.
In the sailing vessel in accordance with the invention, the rigging size may be increased relative to the size of the hull compared with vessels balanced by means of gravity. The speed in water thus is higher also in weak winds and the possibility of attaining speeds may reach levels equal to those obtained wintertime by ice yachts (which are displacement-balanced).
According to a further aspect of the invention, the sailing vessel also comprises at least one boom having a width perpendicularly to the plane of extension of the sails, which at least equals the width of the mast and which preferably considerably exceeds said width. In this manner, the leak from the pressure side to the suction side of the sails is reduced, the belly of the sail may be optimised, and consequently the wind can be used more efficiently.
According to a further aspect of the sailing vessel in accordance with the invention, it further comprises two rudder vanes spaced from one another and each projecting from either side of the hull or the prolongation thereof. The arrangement results in less resistance in water, and consequently in higher speeds.